This invention relates to a regulated draw frame for a sliver bundle composed of cotton or chemical fibers or the like and is of the type which has at least one draw field, a regulated drive system for determining the extent of draw in the draw field, a programmable control device for the drive system and at least one sensor to determine the mass of the running fiber per length unit at a measuring location. A signal determining the extent of draw is stored for a predetermined period in a memory of the control device. Information for adapting and/or determining the quality of the input slivers is extracted from the stored values. Such information is to include, for example, the CV value of the input sliver bundle, its spectrogram and/or its length variation curve. The signal determining the extent of draw may be an output signal of a sensor or a setting signal for the drive system. Sliver sensors at the intake end and at the outlet end of the draw unit are provided for measuring the mass fluctuations of the slivers.
The above-outlined conventional arrangement has, among others, the following disadvantages:
The adaptation of the draw unit is limited to the regulation of the principal drawing process, that is, to an rpm regulation of the drive motors for the rolls of the draw unit. The information is to be gleaned only from data relating to the input sliver bundle. Obtaining the information has to be performed by a complex system and further, the adaptation is provided only for a certain processed fiber lot.